Brake Drum Parts and Types Explored

The drum braking system works just like a disc braking system. But unlike disc brakes that use a brake disc rotor, drum brakes use a brake drum. Drum brakes are commonly outfitted to the rear wheels of small and compact vehicles. It has an enclosed cylindrical structure, and here is how it works.

When you depress the brake pedal, hydraulic pressure created by the master cylinder passes through the brake fluid tube and moves the piston in the wheel cylinder. The piston pushes against the brake shoes, which in turn creates friction against the rotating drum attached to the wheel. And the frictional force stops the moving wheel.

In the same manner, when you drag the emergency brake lever, the brake cables will expand the linings against the rotating brake drum. The system is, however, able to do this with several components. But before discussing brake drum parts, let’s see brake drum types.

brake drum parts diagram

Types of Brake drum

There are three types of brake drums, each differentiated by how the shoes squeeze against the drum. They include the lead/trail, dual leading, and duo servo brake drum.

Lead/trailing shoe brake drum

This type of brake drum has only one of the shoes hitting against the brake drum to provide the braking force. Here, the lead shoe is the one facing the direction the drum rotates to, while the trailing shoe is at the other side. The leading shoe is pulled into the drum’s frictional surface to generate braking force.

In contrast, the trailing shoe is pulled away from friction and, therefore, won’t provide any braking force. So typically, this type of drum brake uses only one brake shoe to generate braking force to stop your car. This brake drum type comes in handy in forward and reverse braking and is mostly outfitted to the rear wheels of passenger vehicles.

Twin leading brake drum

This type of brake drum uses two leading shoes and two wheel cylinders, with each cylinder pressing on one shoe. Meaning both shoes face the direction of the drum’s rotation. So during braking, both shoes push against the brake drum to generate friction, regardless of the direction.

Hence, providing maximum braking. Generally, twin leading brakes provide better braking than lead/trailing shoe brake drums since two shoes generate braking power. And are commonly used in trucks and commercial cars.

Duo servo brake drum

The duo servo brake is an improvement to the dual-leading brake design. Here, two brake shoes are used—primary and secondary and are linked by an adjuster.

When the wheel cylinder presses the primary shoe against the drum, the force generated is then transmitted to the secondary shoe. Hence, providing a huge braking force. This type of brake drum is used for commercial vehicles requiring a huge braking force.

Brake drum parts

Drum brakes are commonly found in small and compact vehicles and are outfitted to their rear wheels. It has an enclosed cylindrical structure, meaning all the components of the drum brakes are enclosed in a cylindrical shape design. And works collectively to slow or bring your car to a stop. So here are parts of drum brakes and their functions.

Brake drum

The brake drum is a large metal disc usually made of cast iron. They are attached to the wheel hub with lug nuts and rotate with the wheel hub. In a disc braking system, a brake disc serves as the rotor, while in a drum braking system, the brake drum is the rotor.

They practically provide the friction that stops the car when pushed by the brake shoes. Here, as the brake drum slows or stops, so does your vehicle.

Wheel Brake Cylinder

The wheel cylinder brake drum parts, also called the brake master, connect to the brake fluid tube via a nut. It houses a piston that comes out when you apply the brake. The force from the piston pushes the brake shoe against the brake drum to slow or stop your car.

Brake shoes

The brake shoe is a half-moon-looking metal on which the pads are glued. It presses on the brake drum (rotor), creating friction to stop your car.

Return or retract the spring

When you hit the brake pedal, the pistons displace the brake shoes by pushing them toward the brake drum. The job of this spring is to return the brake shoes to their original position when the brake is released.


The drum brake self-adjuster helps create a space between the brake shoes and brake drum to avoid contact between them, especially while driving or parked.

Backing plate

The backing plate, usually made of stamped steel, is attached to the rear axle assembly and helps support the brake drum parts assembly. It comes with various holes for holding the springs, wheel cylinder, brake cables, etc.

cheap brake drum parts


Q: What parts are usually replaced on drum brakes?

The brake shoes are part drum brake components most likely to be replaced. The shoes are made of frictional material and regularly push against the brake drum. So they are likely to wear out first, though at a slow rate. The other part usually replaced during a brake drum replacement is the brake drums since they help stop the wheel.

However, in many cases, the drums may need only machining because drum brakes are placed at the rear wheels. And provide just a little amount of braking and keep the car stable. Unless you’re driving a truck that has much weight at the rear, drums don’t take abuse like disc rotors.

While the shoes and drums are mostly replaced during a brake job, also check the conditions of other drum brake parts like the springs, wheel cylinder, self-adjuster, etc. Because while these components may last a long time, they may regularly need servicing to keep them functioning well.

Q: What are the two main parts of drum brakes?

The two main components of a drum brake are brake drums and brake shoes. The brake drums are half circular metal installed on the wheel and spin along with the wheel. The brake shoes are made of frictional material and push against the brake drum when braking. This shoe’s frictional material creates friction on the drum, slowing it down. As the brake drum slows or stops, so do your wheels.

Q: What holds the components of the drum brake assembly?

The component that holds the drum brake parts assembly is the backing plate. The backing plate is attached to the rear axle assembly and made of stamped steel. It has several holes that help hold the brake cables, spring, and wheel cylinder and also support the shoe pads.

Q: Do drum brakes use brake fluid?

Yes. Brake fluid comes handy in converting hydraulic pressure into a braking force during braking. Here is how the brake fluid plays its role. When hydraulic pressure is created in the master cylinder, a tube containing brake fluid linking to the wheel cylinder helps convert this pressure into force.

When the force meets with the pistons inside the wheel cylinder, the pistons, in turn, push against the brake shoes. The shoes then pushe against the drum, creating friction to stop your car.

Q: What does the brake drum attach to?

The brake drum is attached to the wheel hub via lug nuts and spins with the wheel. They are often made of cast iron and provide the friction to stop your car. Basically, as the brake drum (rotor) stops, so do your wheels.

Final Words

The brake drum parts work collectively to bring a car to a stop. This braking system is usually placed on the rear wheels of small and compact cars and uses drums instead of discs to stop your vehicle. While it doesn’t provide most of the braking,

it still needs to work well and therefore needs maintenance and changing of work parts. Here, you’ll need a rear drum brake hardware kit.

The drum brake hardware kit includes everything required to do the job, like the brake spring, shoe pins, return spring, adjusting screws, levers, and parking brake springs. Lastly, while purchasing parts needed to replace drum brakes, go for quality and ones that fit. A motorcycle drum brake parts will not work in a car. Likewise, cheap brake drum parts will not function effectively as quality brake drum parts.


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